For several pages I use a .Count inside a foreach loop
#model ICollection<Item>
foreach(var item in Model)
{
#item.Flight.FlightReservations.count
}
Because of lazy loading the EF makes a round trip to the database for this.
Now I want to fix this by using this or linq version:
Include("List.Flight.FlightReservations")
Doing this makes loading my dbSet take even longer than those foreach round trips
How can I 'load' parts of only 1 object?
I would like to use context.Items.Single(p => p.id == id).Include(.....)
So I only load 1 item fully.
Or any other solutions for this?
(A way to force load item.List.item2.List inside controller)
Any suggestions are welcome :) Thanks
EDIT : now using
Where(..).ToDictionary(item => item, item => item.Flight.FlightReservations.Count);
Also noticed adding an index to my 'clustered index' table helped a little.
Still slow though
var f = _pr.FindBy(duifid);
var result = (from p in f.IngeschrevenVluchten
select new PrestatieModel
{
Eindpos = p.Eindpositie,
Locatie = p.Vlucht.Locatie.Naam,
AantalInschrijvingen = p.Vlucht.Inschrijvingen.Count(),
Vlucht = p.Vlucht
});
This query executes very fast, making a IEnumerable<Model>. But still it loads very slow once sent to the view.
return PartialView(result);
Related
I'm trying to create a pie chart in asp.net mvc however when I'm trying to fetch the data from sql it displays multiple queries save in database, is their a way to get sum of multiple same queries and load the sum in the pie chart
#(Html.EJS().AccumulationChart("container5")
.Series(sr =>
{
sr.Type(Syncfusion.EJ2.Charts.AccumulationType.Pie)
.XName("Heading")
.YName("Factor_Score")
.Name("Factor_Score")
.Explode(true)
.DataLabel(dl => dl.Visible(true).Name("Factor_Score").Position(Syncfusion.EJ2.Charts.AccumulationLabelPosition.Outside).ConnectorStyle(cs => cs.Type(Syncfusion.EJ2.Charts.ConnectorType.Line).Length("5 %")).Font(ft => ft.Size("14px")))
.Animation(animate => animate.Enable(true))
.Radius("70%")
.StartAngle(0)
.EndAngle(360)
.InnerRadius("0%")
.GroupTo("9")
.GroupMode(Syncfusion.EJ2.Charts.GroupModes.Point)
.DataSource(ViewBag.dataSource1).Add();
})
.EnableSmartLabels(true)
.Tooltip(tp => tp.Enable(true))
.LegendSettings(leg => leg.Visible(true)).Title("Loan Audit Finding Detail Checklist").Render()
Controller:
string a = Heading;
int b = Convert.ToInt32(Factor_Score);
PieChartData_Data_View.Add(new PieChartSourceDataData_View(a, b));
[1
For me to give you a complete example I would have to see the whole controller Action. But I assume you would do something like this in the contoller action.
var whateverYouWant = db.YourTable.ToList();
foreach(var arm in whateverYouWant)
{
var sum = arm.ArmQuestions.Count();
}
You would have to load all the categories you wanted to count. You could also do this with a better query like I had posted but without seeing everything, im doing it blind..
I'm attempting to write a search function for a database table that needs to access information from related tables using Entity Framework. However, I'm running into problems getting the data back out of my initial query after doing a join on the parent table and the related tables. My code currently looks like this. I initialize my queryable object
IQueryable<PurchaseOrder> po = _context.PurchaseOrders;
Where PurchaseOrder is an Entity type. Then there is a series of blocks like this.
if (!String.IsNullOrEmpty(searchViewModel.Comment)){
var helper = _context.PurchaseOrderComments.Where(x => x.CommentText.Contains(searchViewModel.Comment));
var mid = po.Join(helper, r => r.PurchaseOrderID, u => u.PurchaseOrderID, (r, u) =>
new
{
PurchaseOrderID = r.PurchaseOrderID,
PurchaseOrderNumber = r.PurchaseOrderNumber,
VendorID = r.VendorID,
ContractNumber = r.ContractNumber,
BuyerUserID = r.BuyerUserID
});
po = mid.Select(x => new PurchaseOrder
{
PurchaseOrderID = x.PurchaseOrderID,
PurchaseOrderNumber = x.PurchaseOrderNumber,
VendorID = x.VendorID,
ContractNumber = x.ContractNumber,
BuyerUserID = x.BuyerUserID
});
}
After each block, po is passed to the next search parameter. However, as you might guess, my program complains that I can't build a complex type in mid's Select statement. I've also tried building PurchaseOrder objects from the contents of mid, inserting them into a new List of PurchaseOrders, and converting that list into a queryable to assign to po to pass on to the next block. However, that changes po's data type from System.Data.Object.ObjectSet to System.Collections.Generic.List, which then throws an InvalidOperationException the next time I try and iterate through it using a foreach.
So my question is, are there any obvious mistakes in my approach or any suggestions for other ways to approach the problem? Thanks very much for any help.
I think you're making this more complicated than it needs to be. If I understand what you're trying to do, you should be able to do something like this:
if (!String.IsNullOrEmpty(searchViewModel.Comment)){
po = po.Where(
o => o.PurchaseOrderComments.Any(
c => c.CommentText.Contains(searchViewModel.Comment)));
}
StriplingWarrior's solution is the best way. In case that your PurchaseOrder class really doesn't have a navigation collection of PurchaseOrderComments (which would force you to use a join) the following should work and is simpler as your double projection:
po=po.Join(helper, r => r.PurchaseOrderID, u => u.PurchaseOrderID, (r, u) => r);
Not sure how this is done, I have my .edmx set up so that the navigation properties match the foreign key relationships on the tables. Not sure if I still need to perform joins or if EF will give me access to the related table data through the navigational properties automatically.
What I need to do it get all the ContentSections and their associated ContentItems based on the ContentView and filtered by the DiversionProgram.CrimeNumber.
I would like to get back IEnumerable, for each ContentSection it should have access to it's ContentItems via the navigation property ContentItems
Thanks
Something like:
using(Entities context = new Entities())
{
IEnumerable<ContentSection> enumerator = context.ContentSections
.Include("ContentItems")
.Where<ContentSection>(cs => cs.ContentView.ContentViewID == someID && cs.ContentItems.Where<ContentItem>(ci => ci.DiversionProgram.CrimeNumber == someCrimeNumber))
.AsEnumerable<ContentSection>
}
I've interpreted
based on the ContentView
as cs.ContentView.ContentViewID == someID
This will give you all the ContentSections for a given ContentView. And interpreted
filtered by the DiversionProgram.CrimeNumber
as cs.ContentItems.Where<ContentItem>(ci => ci.DiversionProgram.CrimeNumber == someCrimeNumber)
which will give you all those ContentItems that have a specific CrimeNumber.
Or did you mean something else with based on / filtered by. Maybe OrderBy, or all those ContentSections where Any of it's ContentItems would have a certain CrimeNumber?
You can eager load to get all associated records, but when you want to start filtering/ordering, don't bother with Include.
Just do a projection with anonymous types and EF will work out what it needs to do. It's a bit hairy, but it'll work. If it get's too complicated, bite the bullet and use a SPROC.
Now, with that caveat, something like this (off the top of my head):
var query = ctx.ContentView
.Select(x => new
{
ContentSections = x.ContentSections
.Where(y => y.ContentItems
.Any(z => z.DivisionProgram.CrimeNumber = 87))
}).ToList().Select(x => x.ContentSections);
If you use the CTP5 you can do something very unique it looks like this:
var context = new YourEntitiesContext();
var query = context.ContentView.Include(cs => cs.ContentSections
.Select(ci => ci.ContentItems
.Select(dp => dp.DiversionProgram)
.Where(dp.CrimeNumber == crimeNumber)))
.Where(cv => cv.ContentViewID == contentViewID).FirtsOrDefault();
You can learn more about the CTP5 and how it can be used in Database first scenario here
var query = from t1 in studentManagementEntities.StudentRegistrations
join t2 in studentManagementEntities.StudentMarks
on t1.StudentID equals t2.StudentID
select new
{
t1.selected column name,
t2.selected column name
};
Hi
How can i filter results exists in BindingSource filled with entities ( using EF 4)?
I tried this:
mybindingsource.Filter = "cityID = 1"
But it seems that binding source with entity framework doesn't support filtering .. am i right ?,is there another way to filter(search) data in binding source .
PS:
- I'm working on windows application not ASP.NET.
- I'm using list box to show the results.
Thanx
Maybe a better one than Leonid:
private BindingSource _bs;
private List<Entity> _list;
_list = context.Entities;
_bs.DataSource = _list;
Now when filtering is required:
_bs.DataSource = _list.Where<Entity>(e => e.cityID == 1).ToList<Entity>;
This way you keep the original list (which is retrieved once from the context) and then use this original list to query against in memory (without going back and forth to the database). This way you can perform all kinds of queries against your original list.
I think, you have made mistake in syntax. You should write Filter like this:
mybindingsource.Filter = "cityID = '1'"
Another way is to use LINQ expressions.
(About LINQ)
Why do you have to call Entety again?
Simple solution:
public List<object> bindingSource;
public IEnumerable FiltredSource
{
get{ return bindingSource.Where(c => c.cityID==1);
}
.where (Function (c) c.cityID = 1)
edit #2: Question solved halfways. Look below
As a follow-up question, does anyone know of a non-intrusive way to solve what i'm trying to do below (namely, linking objects to each other without triggering infinite loops)?
I try to create a asp.net-mvc web application, and get a StackOverFlowException. A controller triggers the following command:
public ActionResult ShowCountry(int id)
{
Country country = _gameService.GetCountry(id);
return View(country);
}
The GameService handles it like this (WithCountryId is an extension):
public Country GetCountry(int id)
{
return _gameRepository.GetCountries().WithCountryId(id).SingleOrDefault();
}
The GameRepository handles it like this:
public IQueryable<Country> GetCountries()
{
var countries = from c in _db.Countries
select new Country
{
Id = c.Id,
Name = c.Name,
ShortDescription = c.ShortDescription,
FlagImage = c.FlagImage,
Game = GetGames().Where(g => g.Id == c.GameId).SingleOrDefault(),
SubRegion = GetSubRegions().Where(sr => sr.Id == c.SubRegionId).SingleOrDefault(),
};
return countries;
}
The GetGames() method causes the StackOverflowException:
public IQueryable<Game> GetGames()
{
var games = from g in _db.Games
select new Game
{
Id = g.Id,
Name = g.Name
};
return games;
}
My Business objects are different from the linq2sql classes, that's why I fill them with a select new.
An unhandled exception of type 'System.StackOverflowException' occurred in mscorlib.dll
edit #1: I have found the culprit, it's the following method, it triggers the GetCountries() method which in return triggers the GetSubRegions() again, ad nauseam:
public IQueryable<SubRegion> GetSubRegions()
{
return from sr in _db.SubRegions
select new SubRegion
{
Id = sr.Id,
Name = sr.Name,
ShortDescription = sr.ShortDescription,
Game = GetGames().Where(g => g.Id == sr.GameId).SingleOrDefault(),
Region = GetRegions().Where(r => r.Id == sr.RegionId).SingleOrDefault(),
Countries = new LazyList<Country>(GetCountries().Where(c => c.SubRegion.Id == sr.Id))
};
}
Might have to think of something else here :) That's what happens when you think in an OO mindset because of too much coffee
Hai! I think your models are recursively calling a method unintentionally, which results in the stack overflow. Like, for instance, your Subregion object is trying to get Country objects, which in turn have to get Subregions.
Anyhow, it always helps to check the stack in a StackOverflow exception. If you see a property being accessed over and over, its most likely because you're doing something like this:
public object MyProperty { set { MyProperty = value; }}
Its easier to spot situations like yours, where method A calls method B which calls method A, because you can see the same methods showing up two or more times in the call stack.
The problem might be this: countries have subregions and subregions have countries. I don't know how you implement the lazy list, but that might keep calling GetCountries and then GetSubRegions and so on. To find that out, I would launch the debugger en set breakpoints on the GetCountries and GetSubRegions method headers.
I tried similar patterns with LinqToSql, but it's hard to make bidirectional navigation work without affecting the performance to much. That's one of the reasons I'm using NHibernate right now.
To answer your edited question, namely: "linking objects to each other without triggering infinite loops":
Assuming you've got some sort of relation where both sides need to know about the other... get hold of all the relevant entities in both sides, then link them together, rather than trying to make the fetch of one side automatically fetch the other. Or just make one side fetch the other, and then fix up the remaining one. So in your case, the options would be:
Option 1:
Fetch all countries (leaving Subregions blank)
Fetch all Subregions (leaving Countries blank)
For each Subregion, look through the list of Countries and add the Subregion to the Country and the Country to the Subregion
Option 2:
Fetch all countries (leaving Subregions blank)
Fetch all Subregions, setting Subregion.Countries via the countries list fetched above
For each subregion, go through all its countries and add it to that country
(Or reverse country and subregion)
They're basically equialent answers, it just changes when you do some of the linking.